Method of fabricating files and the like



Feb. 18, 1958 F. F. HUMBARCI-IER METHOD OF FABRICATING FIL ES AND THE LIKE Filed Sept. 16, 1953 INVENTOR FRANK F. HUMBARGER ATTORNE Unitd Statfis Patent Ofiic P atented Feb. 1a, 1958 METHOD OF FABRICATING FILES AND H LIKE Frank F. Humbarger, Indianapolis, Ind., assignor to Union Carbide Corporation, a corporation of New York Application September 16, 1953, Serial No. 380,561

Claims. (CI. 76?24) The present invention relates to a method of producing files and the like having hard-surfaced work surfaces.

Heretofore, files have been made with integral teeth of steel or other relatively low wear resisting materials and as such were greatly subject to wearing at the work surfaces. When such files are worn, resharpening is required if the files are to be used further. There is a considerable difference of opinion as to the value of a resharpened file.

Therefore, it is the main object of the present invention to provide a method of fabricating files which have hard-surfaced teeth or work surfaces and which have a longer use life.

Other aims and advantages will be apparent from the following description and appended claims.

In the drawing:

Fig. l is a schematic view, partly in cross-section, of an embodiment of the invention wherein a file blank is shown being processed to provide a hard-surfaced work surface;

Fig. 2 is a fragmentary view of a cross-section of the hard-surfaced file produced; and

Fig. 3 is an isometric view, greatly magnified, of a portion of a hard-surfaced file produced according to the invention.

In accordance with the process of the present invention, and referring to Fig. l of the drawing, a screen 10 is placedv against the work surface 12 of a file blank 14 of steel or other suitable material. A hard-surface material, such as tungsten carbide, is applied through the screen to the work surface of the file blank in accordance with the flame plating method of copending U. S. application Serial No. 275,332, filed March 7, 1952, by R. H. Poorman et al., and issued on August 2, 1955, as U. S. Patent No. 2,714,563. In that method a comminuted hard-surface material, such as tungsten carbide-cobalt alloy, is suspended in a detonatable mixture which is introduced into an elongated barrel of a detonation gun 16 and ignited. The high velocity detonation wave and expanding hot gaseous combustion products impart energy to the suspended particles 17 which then pass out p the barrel of the gun and are directed against a surface to be coated. Such coatings flame plated with a detonation gun have been found to have extremely low porosity and excellent strength qualities. Coatings varying from 0.0005" to over 0.20" in thickness may be applied depending on the specific application. The flame plated coating deposited in this manner is held to the surface of the base metal by a firm metallurgical bond.

In the depositing of such hard-surface material on the work surface of the file blank through a screen, it is highly desirable to permit the screen to move slightly to prevent the permanent joining, or bonding, of the screen to the file blank.

It has been found that the shape of the file teeth produced is greatly dependent on the angle at which the detonation gun 16 is held relative to the surface of the file blank. As shown in 'Figs. 2 and 3 of the drawing, when the detonation gun 16 is held at an acute angle to the file blank surface 12, the teeth produced are prisms alternately triangular 18 and 'hollowly triangular 20 in vertical cross-section due .to the changing shape of the screen.

When hard-surfaced material is deposited with the detonation gun normal to the Work surface fo the file blank, all the teeth produced are prisms having rectangular bases.

It is to be understood that teeth having shapes between these extremes can be obtained by variation of the angle maintained between the detonation gun and the work surface of the file blank.

Similarly, the diameter and mesh of the screening may be varied to produce a hard-surfaced tooth of the desired height.

Files fabricated in accordance with the present invention, having teeth of tungsten carbide-+12% cobalt alloy, have been extremely resistant to wear and have proven to have a life greatly exceeding that of steel files employed heretofore.

The hard-surface material applied to form film teeth in accordance with present invention may be applied in one pass of the-detonation gun or may be built up in a number of passes. It has been found desirable to build up the teeth with a number of passes where the height of the file teeth to be fabricated exceeds 0.20.

What is claimed is:

l. A method of fabricating a file having hard-surface teeth comprising placing a screen in contact with the work surface of a file blank, applying a deposit of hard-surface material to said work surface of said file blank to form file teeth of hard-surface material on the work surface thereof by detonating a body of gas containing particles of hard-surface material therein and directing the prodnets of said detonation through said screen and against said surface.

2. A method of fabricating files in accordance with claim 1, wherein said screen is moved slightly during the application of said hard-surface material in order to prevent bonding of said screen to said file.

3. A method of fabricating files having hard-surface teeth comprising placing a screen in close proximity with the work surface of a file blank, applying a deposit of hard-surface material to said work surface of said file blank to form file teeth of hard-surface material on the work surface thereof by detonating a body of gas containing particles of hard-surface material therein and directing the products of said detonation through said screen and against said surface.

4. A method of fabricating files in accordance with claim 3, wherein said screen is moved slightly during the application of said hard-surface material in order to prevent bonding of said screen to said file.

5. A method of fabricating files having hard-surface teeth comprising placing a mesh screen in close proximity with the work surface of a file blank; providing, in an elongated barrel having an open end, a detonatable body of a mixture of fuel and oxidizing gas capable of being detonated and a comminuted hard-surface material; igniting said detonatable body of detonatable mixture to produce a detonation and thereby transmit to said comminuted hard-surface material some of the energy of said detonation to eject said comminuted hard-surface material at high temperature and velocity from the open end of said barrel; directing said ejected comminuted hard surface material through said screen and against said work surface of said file blank to form file teeth of hard surface material on the work surface of said file blank.

6. A method of fabricating files in accordance with claim 5, wherein said screen is moved slightly during the application of said hard-surface material in order to prevent bonding of said screen to said file.

7. A method of fabricating files having hard-surface teeth comprising placing a mesh screen in contact with the work surface of a file blank; providing, in an elongated barrel having an open end, a detonatable body of a mixture of fuel and oxidizing gas capable of being detonated and a comminuted hard-surface material; igniting said detonatable body of detonatable mixture to produce a detonation and thereby transmit to said comminuted hard-surface material some of the energy of said detonation to eject said comminuted hard-surface material at high temperature and velocity from the open end of said barrel; directing said ejected comminuted hard-surface material through said screen and against said work surface of said file blank to form file teeth of hard-surface material on the work surface to said file blank.

8. A method of fabricating files in accordance with claim 7, wherein said screen is moved slightly during the application of said hard-surface material in order to prevent bonding of said screen to said file.

9. The method of fabricating a file having hard-surface teeth comprising positioning a screen in contact with a work surface of a file blank; applying a deposit of hardsurface material to said work surface of said file blank by directing an expanding body of hot gaseous combustion products, containing particles of hard-surface material therein, through said screen and against said surface 4 to there form a plurality of individual teeth of homogeneous hard-surface material directly bonded metallurgically to said work surface of said file blank; and removing said screen therefrom.

10. The method of fabricating a file having hard-surface teeth comprising positioning a mesh screen in contact with a work surface of a file blank; applying a deposit of hard-surface material to said work surface of said file blank by directing an expanding body of hot gaseous combustion products, containing particles of hard-surface material therein, at an acute angle to said work surface of said file blank through said mesh screen and against said surface to there form a plurality of individual teeth of homogeneous hard-surface material directly bonded metallurgically to said work surface of said file blank, said teeth being prismatic in shape and generally triangular in one cross-section; and removing said mesh screen therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 1,662,008 Legate Mar. 6, 1928 1,817,311 Hedde Aug. 4, 1931 FOREIGN PATENTS 248,560 Great Britain Mar. 11, 1926 480,157 Great Britain Feb. 17, 1938 588,438 Great Britain May 22, 1947 

